|Publication number||US4539491 A|
|Application number||US 06/399,048|
|Publication date||Sep 3, 1985|
|Filing date||Jul 16, 1982|
|Priority date||Jul 20, 1981|
|Publication number||06399048, 399048, US 4539491 A, US 4539491A, US-A-4539491, US4539491 A, US4539491A|
|Inventors||Akira Nishioka, Yoshihiro Kawanabe, Hiroyuki Takahori, Hideki Fujimoto|
|Original Assignee||Pioneer Electronic Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (12), Non-Patent Citations (1), Referenced by (29), Classifications (12), Legal Events (6)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates to a voltage/current conversion circuit in which an output current is taken out which is proportional to an input voltage.
Shown in FIG. 1 is a prior art voltage/current conversion circuit in which an input voltage Vi is applied to a non-inverting input terminal of an operational amplifier 11 and the output of the latter is applied to the base of a transistor Q1 constituting a current converting stage. The emitter of the transistor Q1 is connected both to a power supply Vcc through a resistor R1 and to the inverting input terminal of the operational amplifier 11. The collector of the transistor Q1 is connected to the collector connected as a transistor Q2 of a diode. The transistor Q2, together with a transistor Q3 having a base commonly connected to the base of the transistor Q2, and emitter resistors R2 and R3 of the transistors Q2 and Q3, respectively, constitutes a current mirror circuit 12.
With such a circuit arrangement where a PNP transistor (Q1) is employed in the current converting stage, it is a usual practice to use a lateral PNP transistor due to the fact that a monolithic IC is relatively simple to fabricate in a IC manufacturing process. The lateral PNP is, however, disadvantageous in that transition frequency fT is low and is degraded in linearity of the current amplification factor hFE in a large current flow region, resulting that a preferrable characteristic has not been obtained.
Although the foregoing disadvantage can be resolved if a vertical PNP transistor is employed, it is disadvantageous in another aspects such that the IC manufacturing process becomes complicated involving a number of manufacturing steps, and therefore the cost for manufacturing the same becomes expensive.
Accordingly, an object of this invention is to provide a voltage/current conversion circuit giving an output current linearly proportional to an input voltage, which circuit is easy to fabricate in forming an IC.
In accordance with the invention, the foregoing and other objects are accomplished by applying an output of an operational amplifier, to one input of which a predetermined input voltage is applied, to bases of first and second transistors, each of the transistors having an emitter resistor, and feeding back the collector output of the first transistor to the other input of the operational amplifier, wherein the output current is taken out from the collector of the second transistor.
In the drawings:
FIG. 1 is a circuit diagram illustrating a prior art voltage/current conversion circuit;
FIG. 2 is a circuit diagram illustrating a preferred embodiment of a voltage/current conversion circuit according to the invention; and
FIG. 3 is a specific circuit diagram of the embodiment shown in FIG. 2.
A preferred embodiment according to the invention will now be described with reference to the accompanying drawings. FIG. 2 is a circuit diagram showing one preferred embodiment according to the invention, in which a predetermined input voltage Vi is applied to a non-inverting input terminal of an operational amplifier 21. To an output terminal of the operational amplifier 21, bases of first and second transistors Q4 and Q5 are commonly connected. The collector of the transistor Q4 is connected both to a power supply Vcc through a resistor R4 and to a non-inverting input terminal of the operational amplifier 21 to thereby form a negative feedback loop. The respective emitters of the transistors Q4 and Q5 are connected to another power supply VEE through emitter resistors R5 and R6, respectively. With the circuit thus arranged, an output current IO is derived from the collector of the transistor Q5. The voltage VA at point A is set to be in phase with the input voltage Vi, and it is assumed that the transistors Q4 and Q5 have equivalent characteristics and the resistance values of the resistors R5 and R6 are equal to each other.
With such a circuit arrangement, the collector current IA of the transistor Q4 must comply with the following condition in order that the voltage VA at point A can be equal to the input voltage Vi.
IA =(Vcc -Vi)/R4 (1)
Here, provided that the current amplification factor hFE of the transistor Q4 is large and the linearity of hFE with respect to the variation in current is good, the emitter current IE of the transistor Q4 becomes equal to IA.
Furthermore, since the transistors Q4 and Q5 have equivalent characteristics and R5 is equal to R6, the collector current IO of the transistor Q5 is expressed as follows:
IO =IA =(Vcc -Vi)/R4 (2)
As is apparent from equation (2), it is possible to derive the output current IO which is in proportional to the input voltage Vi from the collector of the transistor Q5.
A specific circuit diagram of the embodiment shown in FIG. 2 is shown in FIG. 3. The operational amplifier 21 includes transistors Q6 and Q7, the emitters of which are commonly connected so as to effect differential operations. A constant current source 22 is connected to the common juncture point of the aforementioned transistors. Transistors Q8 and Q9 constituting a current mirror circuit in which the collectors of the transistors Q6 and Q7 are commonly connected to the collectors of the transistors Q8 and Q9, respectively, and the bases of the transistors Q8 and Q9 are commonly connected to each other. The base of the transistor Q7 is connected to the collector of the transistor Q4. The input voltage Vi is applied to the base of the transistor Q6 and the output current is derived from the collector of the transistor Q5.
As described, in accordance with the invention, neither lateral PNP transistors nor vertical PNP transistors are employed, the former being low in transition frequency fT and undesirable in linearity of current amplification factor hFE in the large current flowing region, and the latter being complicated in forming with an IC.
Accordingly, the output current which is linear or in proportional to the input voltage is obtainable and furthermore the IC formation can be easily performed according to this invention.
The voltage/current conversion circuits according in the invention is usable to a VCA voltage/current conversion circuit, FM multiplex multiplier circuits, or the like.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3689848 *||May 4, 1970||Sep 5, 1972||Us Navy||Voltage-to-current converter|
|US3694748 *||Jul 19, 1971||Sep 26, 1972||Hekimian Laboratories Inc||Peak-to-peak detector|
|US3866063 *||Oct 23, 1973||Feb 11, 1975||Fairchild Camera Instr Co||Improved rectifying circuit|
|US3991323 *||Mar 19, 1975||Nov 9, 1976||Honeywell Inc.||Pulse duration to current converter|
|US4087758 *||Jul 20, 1976||May 2, 1978||Nippon Electric Co., Ltd.||Reference voltage source circuit|
|US4145649 *||Nov 21, 1977||Mar 20, 1979||Systron-Donner Corporation||Amplitude insensitive voltage-to-current converter and method for conversion|
|US4213081 *||Feb 27, 1978||Jul 15, 1980||Taylor Earnest R||Method and apparatus for charging sealed Ni-Cad batteries|
|US4251743 *||Oct 30, 1978||Feb 17, 1981||Nippon Electric Co., Ltd.||Current source circuit|
|US4274016 *||Feb 7, 1979||Jun 16, 1981||International Telephone And Telegraph Corporation||Voltage-to-current converter|
|US4338527 *||Jun 11, 1980||Jul 6, 1982||Tokyo Shibaura Denki Kabushiki Kaisha||Voltage-current conversion circuit|
|US4354163 *||Apr 30, 1980||Oct 12, 1982||Ford Aerospace & Communications Corporation||High voltage buffer amplifier|
|US4408129 *||Jun 18, 1981||Oct 4, 1983||International Business Machines Corporation||Constant energy drive circuit for electromagnetic print hammers|
|1||*||Sessions, IC Schematic Source Master, Wiley & Sons, New York, 1978, pp. 42 & 47.|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US4766415 *||Sep 29, 1986||Aug 23, 1988||Siemens Aktiengesellschaft||Digital-to-analog converter with temperature compensation|
|US4835421 *||Mar 18, 1988||May 30, 1989||American Telephone And Telegraph Company, At&T Bell Laboratories||Squaring circuits in MOS integrated circuit technology|
|US4896333 *||Aug 4, 1987||Jan 23, 1990||Signetics Corporation||Circuit for generating a trapezoidal current waveform with matched rise and fall times|
|US5115206 *||Nov 8, 1990||May 19, 1992||North American Philips Corp., Signetics Division||Merged differential amplifier and current source|
|US5121082 *||Dec 11, 1990||Jun 9, 1992||Matsushita Electric Industrial Co., Ltd.||Buffer circuit|
|US5319265 *||Oct 26, 1992||Jun 7, 1994||Samsung Electronics Co., Ltd.||Comparator with hysteresis|
|US5381106 *||Oct 28, 1992||Jan 10, 1995||Samsung Electronics Co., Ltd.||Clipper circuitry suitable for signals with fractional-volt amplitudes|
|US5404097 *||Sep 1, 1993||Apr 4, 1995||Sgs-Thomson Microelectronics S.A.||Voltage to current converter with negative feedback|
|US5541539 *||Aug 18, 1993||Jul 30, 1996||Siemens Aktiengesellschaft||Digital current switch|
|US5557220 *||Jul 8, 1994||Sep 17, 1996||Mitsubishi Denki Kabushiki Kaisha||Polarity detector|
|US5764098 *||Jul 24, 1996||Jun 9, 1998||Nec Corporation||Bias circuit|
|US6538477 *||Jul 30, 2001||Mar 25, 2003||Texas Instruments Incorporated||Input buffer for analog-to-digital convertor|
|US6642768 *||Apr 4, 2001||Nov 4, 2003||Advanced Micro Devices, Inc.||Voltage-dependent impedance selector for non-linearity compensation|
|US6937104||Sep 22, 2003||Aug 30, 2005||National Semiconductor Corporation||High speed high current gain operational amplifier|
|US9368165 *||Jan 22, 2014||Jun 14, 2016||SK Hynix Inc.||Current generation circuit and semiconductor device having the same|
|US20020167344 *||Feb 8, 2002||Nov 14, 2002||Gang Zha||Current amplifier structure|
|US20040070428 *||Dec 2, 2002||Apr 15, 2004||Chao-Ching Chen||Circuit for generating a linear current control signal and method thereof|
|US20150036441 *||Jan 22, 2014||Feb 5, 2015||SK Hynix Inc.||Current generation circuit and semiconductor device having the same|
|CN1107892C *||Jul 3, 1997||May 7, 2003||日本电气株式会社||Voltage to current conversion circuit for converting voltage to multiple current outputs|
|CN103425168A *||Mar 29, 2013||Dec 4, 2013||联发科技（新加坡）私人有限公司||Voltage-to-current converter|
|EP0383095A2 *||Jan 31, 1990||Aug 22, 1990||Texas Instruments Incorporated||BiCMOS reference network|
|EP0383095A3 *||Jan 31, 1990||Dec 27, 1991||Texas Instruments Incorporated||Bicmos reference network|
|EP0419821A2 *||Aug 9, 1990||Apr 3, 1991||Sumitomo Electric Industries, Ltd.||Wide dynamic range current source circuit|
|EP0419821A3 *||Aug 9, 1990||Jan 8, 1992||Sumitomo Electric Industries, Ltd.||Wide dynamic range current source circuit|
|EP1018026A1 *||Aug 20, 1998||Jul 12, 2000||Credence Systems Corporation||Load circuit for integrated circuit tester|
|EP1018026A4 *||Aug 20, 1998||Jun 4, 2003||Credence Systems Corp||Load circuit for integrated circuit tester|
|EP1450172A1 *||Aug 20, 1998||Aug 25, 2004||Credence Systems Corporation||Apparatus for producing an output current|
|WO2001075891A2 *||Mar 29, 2001||Oct 11, 2001||Motorola Inc.||Current conveyor and method for readout of mtj memories|
|WO2001075891A3 *||Mar 29, 2001||Jan 31, 2002||Motorola Inc||Current conveyor and method for readout of mtj memories|
|U.S. Classification||330/260, 330/293, 327/103|
|International Classification||H03F3/34, H03F3/347, G05F1/56, G08C19/02, G01D5/14|
|Cooperative Classification||G05F1/561, H03F3/347|
|European Classification||G05F1/56C, H03F3/347|
|Jun 27, 1985||AS||Assignment|
Owner name: PIONEER ELECTRONIC CORPORATION, NO. 4-1, MEGURO 1-
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:NISHIOKA, AKIRA;KAWANABE, YOSHIHIRO;TAKAHORI, HIROYUKI;AND OTHERS;REEL/FRAME:004418/0290
Effective date: 19820709
Owner name: PIONEER ELECTRONIC CORPORATION,JAPAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:NISHIOKA, AKIRA;KAWANABE, YOSHIHIRO;TAKAHORI, HIROYUKI;AND OTHERS;REEL/FRAME:004418/0290
Effective date: 19820709
|Feb 3, 1989||FPAY||Fee payment|
Year of fee payment: 4
|Feb 16, 1993||FPAY||Fee payment|
Year of fee payment: 8
|Apr 8, 1997||REMI||Maintenance fee reminder mailed|
|Aug 31, 1997||LAPS||Lapse for failure to pay maintenance fees|
|Nov 11, 1997||FP||Expired due to failure to pay maintenance fee|
Effective date: 19970903